knh381squatfandomcom-20200214-history
The Squat Wiki
Welcome to the The Squat Wiki Miami University KNH 381 wiki project about the squat and its mechanics- Keith Mueller and Zac Dysert The Squat The squat is a compound, full body movement that is often used to strengthen the muscles of the lower body, specifically the posterior chain. Outside of athletics, the bottom of a full squat is a passive resting position that is an alternative to sitting for lowering the body's center of mass. However, the lifestyle of many Americans leads to limited joint mobility, making a full squat very difficult to achieve. The squat is so commonly used because no other strength training movement involves enough range of motion to use all of the muscles of the posterior chain simultaneously. The squat is also the only movement to preceed the concentric contraction of these muscle groups with an eccentric contraction, taking advantage of a stretch reflex to move the load. In addition to the posterior chain, the muscles of the lower back, abdominals, lateral trunk, and even the shoulders and arms are recruited isometrically to support and maintain a neutral spine through which to transfer kinetic energy to the load, if the movement is loaded. Though the squat is used to target the hamstrings, glutes, quadriceps, and the external rotators of the hips, it is safe to say that a sufficiently heavy squat also recruits an isometric contraction from most of the body's muscle groups. However, the body is wired to think and learn in terms of movements, not muscles, and the squat should be thought of as a motor pattern. In comparing the back squat (BS) and the plyometric jump squat (PSJ), Sugisaki et al (2014) found that "individual muscle recruitment differs between the BS and the PSJ, which does not necessarily correspond with the joint kinetics" (p. 4). These finding support the notion that the squat is a fundamental, archetypal shape for human movement that can be manipulated-through changes in load and type of contraction- to elicit certain adaptations in training. Czaprowski (2012) surveyed 412 Polish students of physical education and personal training. 51% of them admitted to not knowing what a correct squat looks like. Despite this ignorance, the squat has great potential as a tool for developing the strength of the body as a unit, through a large range of motion, and as a diagnostic tool to expose issues in an athlete's motor patterning and mobility that wreak havoc on performance and lead to injuries. Variations The back squat is used to develop strength in the posterior chain muscles of the lower body, as well as the core. It is the most common variation of the squat, and is one of the three movements in competitive powerlifting (The squat, the bench press, and the deadlift). The movement is loaded by a barbell placed across the trapezius muscles. The back squat begins by unracking the weight and stepping back clear of the rack. From a standing position, the athlete sits backward at the hips while externally rotating the femurs, until reaching the bottom position. The bottom is characterized by the mechanical limit of both hip and knee flexion, or the limit of the athletes hip and knee mobility (see depth in the "common faults" section below). The mechanics of the back squat can be affected by the placement of the bar across the top of the back, leading to the use of high-bar and low-bar styles to suit different goals. The front squat is similar to the back squat, however the placement of the load via a barbell across the top of the chest and deltoids (the front rack) changes the mechanics of the movement, and thus is used to elicit a different strength adaptation than the back squat. The front squat is a critical part of the clean and jerk , one of the two movements contested in Olympic weightlifting. A heavy clean is caught in the bottom of a front squat (pictured). The overhead squat, placing the highest demand on the mobility of the hips and ankles, is the most difficult squat variant to learn and execute. It is also a critical skill for Olympic weightlifting, as the catch phase of the snatch is the bottom of an overhead squat. Forces Involved in Squatting ::::: The loaded barbell for a back squat is placed across the shoulders. The lifter and the barbell are a system that has its own center of mass. At any hip, knee or back angle (see picture to the left), this system is the most stable - and the most force would be needed to knock the system over- when that center of mass falls in line with the middle of the foot (dotted line in picture). The force that provides the resistance for the movement is that of gravity acting on the mass of the barbell. This force'' always acts vertically downward, and so the most efficient way to oppose this force is to exert a force that does work on the load along a vertical path in line with the mid-foot. A balanced, stable squat does this. This also means that any work done that results in a movement of the bar in any direction other than vertically downward is not work against the force of gravity, and in addition to wasting energy, can destabilize the system. At one rep max weights, there is almost zero tolerance for deviation from this line of balance, and any movement forward or backward can result in a missed rep. The changes in hip, knee and back angle that accompany the different squat variants are a result of this need for the system to be stable in response to the placement of the load (high/low-bar back rack, front rack, or overhead). ::::: When squatting, both the spine and the femurs form moment arms, with the load exerting a torque on the hip and the knee, respectively. This force is affected by the placing of the load, and thus is the largest determinant of the back angle in the squat (from which the hip and knee angles follow). In the low-bar position of the back squat the moment arm between the bar and the hips is shorter than it would be in the high-bar position. The result is a smaller back angle (a more horizontal back) in order to keep the bar over the balance point that is the mid-foot. If the bar comes forward or rear of this balance point, another moment force comes into play, affecting the stability of the squat. If the bar is out of balance, more force is necessary to move the weight of the load, potentially resulting in a missed rep, or an accident. Learning to Squat: The Goblet Squat as a Teaching Tool The goblet squat is a great movement to perform to learn one of the most critical aspects of squatting: "shoving the knees out" laterally by externally rotating the femurs as you descend to the bottom position. Coach Dan John developed the goblet squat to do just that. The result is an athlete that squats between their knees, not behind them. The goblet squat is performed just like any other squat, with the load held in the hands in front of the body, making it mechanically similar to a front squat, especially in terms of the back angle. With the load (usually a dumbell or kettlebell) held in this position, the elbows get in the way and it becomes impossible to reach full depth without shoving the knees out. The reason for shoving the knees out is to give mechanical stability to the knee joint, avoiding a valgus knee fault, mentioned in the "Common Faults" section below. *Stand up straight with feet straight, within 10 degrees, and the weight on the ground in front of you. *Squeeze your glutes and contract the core to pull your ribcage down and to maintain a neutral spine, do not let go of this braced neutral position until done squatting. Externally rotate the femurs to "screw your feet into the ground", which will stabilize the knee throughout the range of motion of the squat. *Keeping the core braced, hinge forward at the hips and pick up the weight. Hold the weight in front of you at about chest height. *Still maintaing a braced neutral spine. Sit back with the hips, loading the hamstrings, while continuing to externally rotate the femurs to spread the knees out laterally. Keep the shins as vertical as possible. Stop at the limit of your range of motion. *Push through the floor, driving the hips up to return to the start postion, standing up straight. While driving upward, contrinue to contract the core to maintain neutral spine, and shove the knees out to avoid a valgus knee postion (see "common faults section below"). The "up" phase should look identical to the "down" phase, but in reverse. Common Faults The following faults are mistakes that will hurt the performance of any of the variations of the squat, loaded or unloaded. Over time, these movement errors can cause or exacerbate injuries. The skills of manipulating the barbell in the high-bar, low-bar, front rack, and overhead positions each carry their own set of faults, which are not covered here. '''Depth Fault'- For strength training, the minimum acceptable depth for a squat is the top of the femur parallel with the ground. Cotter (2013) found that the largest loads could be lifted at depths above parallel (p. 1769), which follows intuition that the highest 1RM will be achieved when the load has the least distance to travel. A full depth "butt to ankles" squat uses the movement to it's fullest potential, eliciting the greatest strength adaptations and maximizing the squat's potential as a diagnostic tool. Eliminating any issues with mobility and motor control that prevent proper depth should the the athlete's first priority if they wish to take advantage of all the squat has to offer. Knee Forward Fault- A knee-forward fault is usually the result of initiating the squat by shifting forward at the knees. A correct squat begins by sitting the hamstrings back and loading those tissues first, and therefore maximally. Loading the knees first does just that, and can result in lots of shear stress on the tissues of the knee joint. Czaprowski (2012) warns that the dominance of knee joints durning the squat leads to an increase in moments of both shear and compressive forces (p. 3). In addition, this poor techinique has the effect of "taking up the slack" of useful ankle range of motion very early in the movement. While a mobility issue can reinforce this error, it is usually the result of a motor control issue, and once the athlete is taught correct technique, the fault dissapears. Spinal Fault- There are two kinds of spinal faults, resulting from a failure to organize the spine in a neutral position. During the squat, this manifests itself as a rounded or overextended back in the bottom position, and vertebrae that move and shear under load throughout the range of motion. The compression force transmitted by the load to the vertebrae causes this shear. The rigid spine is a moment arm. If it is not rigid, the body essentially has as many hip joints as there are moving vertebrae, resulting in a loss of force transmitted to the load. This fault is remedied through the bracing sequence described above, as well as the strength/motor control to maintain that neutral spine with a contraction of the core. Valgus Knee Fault- Results from a failure to create external rotation torque to stabilize the knee. "Shoving the knees" out is an exaggerated position that helps to avoid a valgus fault as a heavy load will tend to enforce this mechanically stable, but passive and weak position from which to exert force on the load. Pushing the knees out laterally, slightly past the feet also brings the posterior tibialis on tension, which creates a stable arch in the foot. This fault can be fixed by "screwing the feet into the ground from the beginning of the movement. The point is not to have the knees as far laterally as possible, but to resist the tendency of the knees to default to a valgus position. Don't think "Knees out". Think "Knees not in". Open Foot Fault- If the feet are turned out past 10-15 degrees, the arch of the foot collapses, and the demands on hip mobility to be able to torque the knees laterally past the feet become much greater. Shuyang (2013) found that turned out feet cause the knee to internally rotate as the hip flexes during the down phase of the squat (p. 61). This tendency lends itself to a much less stable bottom position from which to transmit force to the load. The same study concluded that the squat should be performed with feet neutral (facing forward), "especially when performed with heavy resistance" (p. 64). This fault is often the result of a lack of mobility in the hips, which have to "dump" torque being generated by external rotation at the hip. Missing range of motion at the ankle joint can also cause a compromise, where the feet turn out to buy more range of motion for the ankle, so the knees can continue to track forward and the spine can remain neutral. Head Fault- The neck is part of the spine, and the spine is not in it's best neutral position to transmit force if the athlete bends the neck to look up. A "head up" coaching cue is often used to avoid rounding the lower back, but it simply puts a kink in another part of the spine, where shear of the vertebrae will still happen under load. A good fix for this fault is to keep the eyes on one spot on the floor while squatting, and imagine pinching a tennis ball between your neck and your chin. Links The following links provide usefull resources for learning to squat, strategies for increasing mobility, and programming. mobilitywod.com startingstrength.com gymnasticswod.com Sources #Starret, Kelly, and Glen Cordoza. Becoming a supple leopard: the ultimate guide to resolving pain, preventing injury, and optimizing athletic performance, 2013. Print. #Shuyang, H., Shirong, G., Hongtao, L. & Rong, L. (2013). Alterations in Three-dimensional Knee Kinematics and Kinetics during Neutral, Squeeze, and Outward Squat. Journal of Human Kinetics 3959-66. #Sugisaki, N., Kurokawa, S., Okada, J., & Kanehisa, H. (2014). Difference in the Recruitment of Hip and Knee Muscles between Back Squat and Plyometric Squat Jump. Plos ONE. 9(6), 1-9. #Czaprowski, D., Biernat, R., & Kedra, A. (2012). Squat- Rules of Performing and Most Common Mistakes: Squat- methodology of teaching. Polish Journal of Sports & Tourism. '' 19 (1). 3-12. #Czaprowski, D., Kedra, A., & Biernat, R. (2012). Students' Knowledge Concerning the Correct Squat and the Elements of the Methodology of Teaching it. ''Baltic Journal of Health & Physical Activity. 4(2). 124-131. #Cotter, J., Chaudhari, A., Jamison, S., & Devor, S. (n.d). Knee Joint Kinetics in Relation to Commonly Prescribed Squat Loads and Depths. Journal of Strength and Conditioning Research. 27(7), 1765-1774. Category:Browse Category:Sources